Patent Document 1 discloses a non-volatile switching device. FIGS. 8A and 8B show a conventional non-volatile switching device disclosed in FIG. 3 of Patent Document 1.
As shown in FIG. 8A, the non-volatile switching device comprises a substrate 11, a control electrode 12, a ferroelectric layer 13, a semiconductor layer 14, and first to third electrodes 15a to 15c. The control electrode 12, the ferroelectric layer 13, and the semiconductor layer 14 are stacked in this order on the substrate 11. The first to third electrodes 15a to 15c are provided on the semiconductor layer 14.
A voltage is applied between the control electrode 12 and the first to third electrodes 15a to 15c to change the polarization direction of the ferroelectric layer 13.
In a case where a part of the ferroelectric layer 13 has an upward polarization direction, the part of the semiconductor layer 14 stacked on the part of the ferroelectric layer 13 has low resistance. This corresponds to the ON-state.
On the contrary, in a case where a part of the ferroelectric layer 13 has a downward polarization direction, the part of the semiconductor layer 14 stacked on the part of the ferroelectric layer 13 has high resistance. This corresponds to the OFF-state.
In FIG. 8A, only the part of the ferroelectric layer 13 positioned below the third electrode 15c has a downward polarization direction. Accordingly, as shown in FIG. 8B, a current flows selectively from the first electrode 15a to the second electrode 15b. 